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1.
Five new compounds, eupatodibenzofuran A (1), eupatodibenzofuran B (2), 6-acetyl-8-methoxy-2,2-dimethylchroman-4-one (3), eupatofortunone (4), and eupatodithiecine (5), have been isolated from the aerial part of Eupatorium fortunei, together with 11 known compounds (6‒16). Compounds 1 and 2 featured a new carbon skeleton with an unprecedented 1-(9-(4-methylphenyl)-6-methyldibe nzo[b,d]furan-2-yl)ethenone. Among the isolates, compound 1 exhibited potent inhibitory activity with IC50 values of 5.95 ± 0.89 and 5.55 ± 0.23 μM, respectively, against A549 and MCF-7 cells. The colony-formation assay demonstrated that compound 1 (5 μM) obviously decreased A549 and MCF-7 cell proliferation, and Western blot test confirmed that compound 1 markedly induced apoptosis of A549 and MCF-7 cells through mitochondrial- and caspase-3-dependent pathways.  相似文献   

2.
The objectives of this investigation were to produce a novel chitosanase for application in industries and waste treatment. The transformation of chitinous biowaste into valuable bioactive chitooligomers (COS) is one of the most exciting applications of chitosanase. An amphiprotic novel chitosanase from Bacillus mycoides TKU038 using squid pen powder (SPP)-containing medium was retrieved from a Taiwan soil sample, which was purified by column chromatography, and characterized by biochemical protocol. Extracellular chitosanase (CS038) was purified to 130-fold with a 35% yield, and its molecular mass was roughly 48 kDa. CS038 was stable over a wide range of pH values (4–10) at 50 °C and exhibited an optimal temperature of 50 °C. Interestingly, the optimum pH values were estimated as 6 and 10, whereas CS038 exhibited chitosan-degrading activity (100% and 94%, respectively). CS038 had Km and Vmax values of 0.098 mg/mL and 1.336 U/min, separately, using different concentrations of water-soluble chitosan. A combination of the high performance liquid chromatography (HPLC) and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometer data revealed that the chitosan oligosaccharides obtained from the hydrolysis of chitosan by CS038 comprise oligomers with multiple degrees of polymerization (DP), varying from 3–9, as well as CS038 in an endolytic fashion. The TKU038 culture supernatant and COS mixture exhibited 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activities. The COS activities were dose dependent and correlated to their DP. The COS with high DP exhibited enhanced DPPH radical scavenging capability compared with COS with low DP. Furthermore, the COS exhibited inhibitory behavior on nitric oxide (NO) production in murine RAW 264.7 macrophage cells, which was induced by Escherichia coli O111 lipopolysaccharide (LPS). The COS with low DP possesses a more potent anti-inflammatory capability to decrease NO production (IC50, 76.27 ± 1.49 µg/mL) than that of COS with high DP (IC50, 82.65 ± 1.18 µg/mL). Given its effectiveness in production and purification, acidophilic and alkalophilic properties, stability over ranges of pH values, ability to generate COS, antioxidant activity, and anti-inflammatory, CS038 has potential applications in SPP waste treatment and industries for COS production as a medical prebiotic.  相似文献   

3.
The growth of iron silicides on Si (111) using reactive deposition epitaxy method was studied by scanning tunneling microscopy and X-ray photoelectron spectroscopy (XPS). Instead of the mixture of different silicide phases, a homogeneous crystalline film of c (4 × 8) phase was formed on the Si (111) surface at approximately 750°C. Scanning tunneling spectra show that the film exhibits a semiconducting character with a band gap of approximately 0.85 eV. Compared with elemental Fe, the Fe 2p peaks of the film exhibit a lower spin-orbit splitting (−0.3 eV) and the Fe 2p3/2 level has a smaller full-width at half maximum (−0.6 eV) and a higher binding energy (+0.3 eV). Quantitative XPS analysis shows that the c (4 × 8) phase is in the FeSi2 stoichiometry regime. The c (4 × 8) pattern could result from the ordered arrangement of defects of Fe vacancies in the buried Fe layers.  相似文献   

4.
The aims of this study were to develop the magnolol–chitosan films and study the positive effect of the combination of magnolol and chitosan. The addition of magnolol made the magnolol–chitosan films exhibit higher density (1.06–1.87 g/cm3), but the relatively lower water vapor permeability (12.06–7.36 × 10−11·g·m−1·s−1·Pa−1) and water content (16.10–10.64%). The dense and smooth surface and cross-section of magnolol–chitosan films were observed by environmental scanning electron microscopy (ESEM) images. The interaction of magnolol and chitosan was observed by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). After the addition of magnolol, the antioxidant capacity of magnolol–chitosan films was increased from 18.99 to 82.00%, the growth of P. aeruginosa was inhibited and the inhibition percentage of biofilm formation was increased from 30.89 to 86.04%. We further verified that the application of magnolol–chitosan films on chilled pork significantly reduced the increases in pH value, inhibited the growth of microorganisms and extended the shelf life. Results suggest that magnolol had a positive effect on magnolol–chitosan films and could be effectively applied to pork preservation.  相似文献   

5.
Facile synthesis of poly (N,N-dimethylaminoethyl methacrylate) (PDMAEMA) star polymers on the basis of the prepolymer chains, PDMAEMA as the macro chain transfer agent and divinyl benzene (DVB) as the cross-linking reagent by reversible addition-fragmentation chain transfer (RAFT) polymerization was described. The RAFT polymerizations of DMAEMA at 70 °C using four RAFT agents with different R and Z group were investigated. The RAFT agents used in these polymerizations were dibenzyl trithiocarbonate (DBTTC), s-1-dodecyl-s''-(α,α''-dimethyl-α-acetic acid) trithiocarbonate (MTTCD), s,s''-bis (2-hydroxyethyl-2''-dimethylacrylate) trithiocarbonate (BDATC) and s-(2-cyanoprop-2-yl)-s-dodecyltrithiocarbonate (CPTCD). The results indicated that the structure of the end-group of RAFT agents had significant effects on the ability to control polymerization. Compared with the above-mentioned RAFT agents, CPTCD provides better control over the molecular weight and molecular weight distribution. The polydispersity index (PDI) was determined to be within the scope of 1.26 to 1.36. The yields, molecular weight, and distribution of the star polymers can be tuned by changing the molar ratio of DVB/PDMAEMA-CPTCD. The chemical composition and structure of the linear and star polymers were characterized by GPC, FTIR, 1H NMR, XRD analysis. For the pure Chitosan membrane, a great improvement was observed for both CO2 permeation rate and ideal selectivity of the blending composite membrane upon increasing the content of SPDMAEMA-8. At a feed gas pressure of 37.5 cmHg and 30 °C, the blinding composite membrane (Cs: SPDMAEMA-8 = 4:4) has a CO2 permeation rate of 8.54 × 10−4 cm3 (STP) cm−2∙s−1∙cm∙Hg−1 and a N2 permeation rate of 6.76 × 10−5 cm3 (STP) cm−2∙s−1∙cm∙Hg−1, and an ideal CO2/N2 selectivity of 35.2.  相似文献   

6.
7.
A novel series of N-substituted cis- and trans-3-aryl-4-(diethoxyphosphoryl)azetidin-2-ones were synthesized by the Kinugasa reaction of N-methyl- or N-benzyl-(diethyoxyphosphoryl)nitrone and selected aryl alkynes. Stereochemistry of diastereoisomeric adducts was established based on vicinal H3–H4 coupling constants in azetidin-2-one ring. All the obtained azetidin-2-ones were evaluated for the antiviral activity against a broad range of DNA and RNA viruses. Azetidin-2-one trans-11f showed moderate inhibitory activity against human coronavirus (229E) with EC50 = 45 µM. The other isomer cis-11f was active against influenza A virus H1N1 subtype (EC50 = 12 µM by visual CPE score; EC50 = 8.3 µM by TMS score; MCC > 100 µM, CC50 = 39.9 µM). Several azetidin-2-ones 10 and 11 were tested for their cytostatic activity toward nine cancerous cell lines and several of them appeared slightly active for Capan-1, Hap1 and HCT-116 cells values of IC50 in the range 14.5–97.9 µM. Compound trans-11f was identified as adjuvant of oxacillin with significant ability to enhance the efficacy of this antibiotic toward the highly resistant S. aureus strain HEMSA 5. Docking and molecular dynamics simulations showed that enantiomer (3R,4S)-11f can be responsible for the promising activity due to the potency in displacing oxacillin at β-lactamase, thus protecting the antibiotic from undesirable biotransformation.  相似文献   

8.
9, 10-bis(3,5-dihydroxyphenyl)anthracene (BDHA) and 2,2′,4,4′-tetrahydroxybenzophenone (THB) are crystallized with bipyridine bases 4,4′-bipyridyl (bipy), 1,2-bis(4-pyridyl)ethane (bipy-eta), 1,2-di(4-pyridyl)ethylene (dipy-ete), 1,3-di(4-pyridyl)propane (dipy-pra), 4,4′-dipyridyl sulfide (dipy-sul), and 4,4′-dipyridyl disulfide (dipy-dis) to afford molecular complexes (BDHA)·(bipy)21, (BDHA) · (bipy-eta)22, (BDHA)0.5· (dipy-pra) ·CH3CH2OH 3, (BDHA)0.5· (dipy-sul) ·H2O 4, (BDHA)0.5· (dipy-dis) ·CH3CH2OH 5 and (THB) · (dipy-ete)2·H2O 6. The crystal structures of 1–6 have been determined by single-crystal X-ray diffraction. All these molecular complexes exhibit polymeric supramolecular structures via O–H· · ·N or O–H· · ·O hydrogen-bonding. 1 and 2 form infinitely rectangular macrocycles linked with one another, whose sizes are ca.12.477 å × 4.802 å and ca.14.575 å × 4.809 å, respectively. 3, 5 and 6 form the one-dimensional zigzag chain structure. 4 forms a ladder structure, and two dipy-sul molecules were included in a frame.  相似文献   

9.
Two new triterpenoids, 2α,3β-dihydroxyolean-11,13(18)-dien-19β,28-olide (1) and 3β,5β-dihydroxyglutinol (2), together with eight known compounds (3–10) were isolated from the roots of Rhaphiolepis indica var. tashiroi (Rosaceae). The structures of 1–10 were determined by spectroscopic techniques. Among these isolates, 2α,3β-dihydroxyolean-13(18)-en-28-oic acid (9) exhibited inhibitory effect on N-formyl-methionyl-leucyl-phenylalanine (fMLP)-induced superoxide production, with an IC50 value of 16.50 μM.  相似文献   

10.
Chitosan-coated magnetic nanoparticles (CMNP) were obtained at 70 °C and 80 °C in a one-step method, which comprises precipitation in reverse microemulsion in the presence of low chitosan concentration in the aqueous phase. X-ray diffractometry showed that CMNP obtained at both temperatures contain a mixture of magnetite and maghemite nanoparticles with ≈4.5 nm in average diameter, determined by electron microscopy, which suggests that precipitation temperature does not affect the particle size. The chitosan coating on nanoparticles was inferred from Fourier transform infrared spectrometry measurements; furthermore, the carbon concentration in the nanoparticles allowed an estimation of chitosan content in CMNP of 6%–7%. CMNP exhibit a superparamagnetic behavior with relatively high final magnetization values (≈49–53 emu/g) at 20 kOe and room temperature, probably due to a higher magnetite content in the mixture of magnetic nanoparticles. In addition, a slight direct effect of precipitation temperature on magnetization was identified, which was ascribed to a possible higher degree of nanoparticles crystallinity as temperature at which they are obtained increases. Tested for Pb2+ removal from a Pb(NO3)2 aqueous solution, CMNP showed a recovery efficacy of 100%, which makes them attractive for using in heavy metals ion removal from waste water.  相似文献   

11.
Two supramolecular coordination polymers, [HgI2(L1)·0.5H2O] (1) and [HgI2(L2)·0.4CH3OH] (2), have been prepared by ligands L1 (L1 = bis[4-(4- pyridylmethyleneamino)phenyl] ether) and L2 (L2 = N,N′-bis(3-pyridylmethyl)-diphthalic diimide) with HgI2, respectively. 1 formed an interestingly infinite cross-linked double helical structure, whereas 2 formed the one-dimensional zigzag chains, which are parallel with each other.  相似文献   

12.
La2Zr2O7 (LZO) films were grown on different buffer architectures by radio frequency magnetron sputtering for the large-scale application of YBa2Cu3O7−x (YBCO)-coated conductors. The three different buffer architectures were cerium oxide (CeO2), yttria-stabilized zirconia (YSZ)/CeO2, and CeO2/YSZ/CeO2. The microstructure and surface morphology of the LZO film were studied by X-ray diffraction, optical microscopy, field emission scanning electron microscopy, and atomic force microscopy. The LZO films prepared on the CeO2, YSZ/CeO2, and CeO2/YSZ/CeO2 buffer architectures were preferentially c-axis-oriented and highly textured. The in-plane texture of LZO film on CeO2 single-buffer architecture was ∆ φ = 5.5° and the out-of-plane texture was ∆ ω = 3.4°. All the LZO films had very smooth surfaces, but LZO films grown on YSZ/CeO2 and CeO2/YSZ/CeO2 buffer architectures had cracks. The highly textured LZO film grown on CeO2-seed buffered NiW tape was suitable for the epitaxial growth of YBCO film with high currents.  相似文献   

13.
The objective of the present study was to determine the antimicrobial resistance profile of planktonic and biofilm cells of Staphylococcus aureus and coagulase-negative staphylococci (CoNS). Two hundred Staphylococcus spp. strains were studied, including 50 S. aureus and 150 CoNS strains (50 S. epidermidis, 20 S. haemolyticus, 20 S. warneri, 20 S. hominis, 20 S. lugdunensis, and 20 S. saprophyticus). Biofilm formation was investigated by adherence to polystyrene plates. Positive strains were submitted to the broth microdilution method to determine the minimum inhibitory concentration (MIC) for planktonic and biofilm cells and the minimal bactericidal concentration for biofilm cells (MBCB). Forty-nine Staphylococcus spp. strains (14 S. aureus, 13 S. epidermidis, 13 S. saprophyticus, 3 S. haemolyticus, 1 S. hominis, 3 S. warneri, and 2 S. lugdunensis) were biofilm producers. These isolates were evaluated regarding their resistance profile. Determination of planktonic cell MIC identified three (21.4%) S. aureus strains that were resistant to oxacillin and six (42.8%) that were resistant to erythromycin. Among the CoNS, 31 (88.6%) strains were resistant to oxacillin, 14 (40%) to erythromycin, 18 (51.4%) to gentamicin, and 8 (22.8%) to sulfamethoxazole/trimethoprim. None of the planktonic isolates were resistant to vancomycin or linezolid. MICs were 2-, 4-, 8-, and up to 16-fold higher for biofilm cells than for planktonic cells. This observation was more common for vancomycin and erythromycin. The MBCB ranged from 8 to >256 µg/mL for oxacillin, 128 to >128 µg/mL for vancomycin, 256 to >256 µg/mL for erythromycin and gentamicin, >64 µg/mL for linezolid, and 32/608 to >32/608 µg/mL for sulfamethoxazole/trimethoprim. The results showed considerably higher MICs for S. aureus and CoNS biofilm cells compared to planktonic cells. Analysis of MBCM confirmed that even high concentrations of vancomycin were unable to eliminate the biofilms of S. aureus and CoNS species. Linezolid was the most effective drug in inhibiting staphylococci in the biofilm, without an increase in the MIC, when compared to planktonic cells. None of the isolates were resistant to this drug.  相似文献   

14.
In this work, the acridine nucleus was used as a lead-compound for structural modification by adding different substituted thiosemicarbazide moieties. Eight new (Z)-2-(acridin-9-ylmethylene)-N-phenylhydrazinecarbothioamide derivatives (3a–h) were synthesized, their antiproliferative activities were evaluated, and DNA binding properties were performed with calf thymus DNA (ctDNA) by electronic absorption and fluorescence spectroscopies. Both hyperchromic and hypochromic effects, as well as red or blue shifts were demonstrated by addition of ctDNA to the derivatives. The calculated binding constants ranged from 1.74 × 104 to 1.0 × 106 M−1 and quenching constants from −0.2 × 104 to 2.18 × 104 M−1 indicating high affinity to ctDNA base pairs. The most efficient compound in binding to ctDNA in vitro was (Z)-2-(acridin-9-ylmethylene)-N-(4-chlorophenyl) hydrazinecarbothioamide (3f), while the most active compound in antiproliferative assay was (Z)-2-(acridin-9-ylmethylene)-N-phenylhydrazinecarbothioamide (3a). There was no correlation between DNA-binding and in vitro antiproliferative activity, but the results suggest that DNA binding can be involved in the biological activity mechanism. This study may guide the choice of the size and shape of the intercalating part of the ligand and the strategic selection of substituents that increase DNA-binding or antiproliferative properties.  相似文献   

15.
This article sets out a method for producing chitin and chitosan by Cunninghamella elegans and Rhizopus arrhizus strains using a green metabolic conversion of agroindustrial wastes (corn steep liquor and molasses). The physicochemical characteristics of the biopolymers and antimicrobial activity are described. Chitin and chitosan were extracted by alkali-acid treatment, and characterized by infrared spectroscopy, viscosity and X-ray diffraction. The effectiveness of chitosan from C. elegans and R. arrhizus in inhibiting the growth of Listeria monocytogenes, Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella enterica, Escherichia coli and Yersinia enterocolitica were evaluated by determining the minimum inhibitory concentrations (MIC) and the minimum bactericidal concentrations (MBC). The highest production of biomass (24.60 g/L), chitin (83.20 mg/g) and chitosan (49.31 mg/g) was obtained by R. arrhizus. Chitin and chitosan from both fungi showed a similar degree of deacetylation, respectively of 25% and 82%, crystallinity indices of 33.80% and 32.80% for chitin, and 20.30% and 17.80% for chitosan. Both chitin and chitosan presented similar viscosimetry of 3.79–3.40 cP and low molecular weight of 5.08 × 103 and 4.68 × 103 g/mol. They both showed identical MIC and MBC for all bacteria assayed. These results suggest that: agricultural wastes can be produced in an environmentally friendly way; chitin and chitosan can be produced economically; and that chitosan has antimicrobial potential against pathogenic bacteria.  相似文献   

16.
A chitosan resin derivatized with Schiff bases was synthesized by using a crosslinked chitosan (CCTS) as base material. We first synthesized N-benzylidene chitosan (CTB) by the reaction of benzaldehyde with chitosan. After this reaction crosslinking was carried out in the usage of epichlorohydrine (ECH) as a crosslinking agent. The Schiff base was removed by reacting diluted ethyl alcohol hydrochloride solution to give crosslinked chitosan (CCTS).The CCTS was suspended in a mixture of ethyl alcohol/deionized water followed by the addition of epichlorohydrine and by this way crosslinked chitosan-epichlorhydrine (CCTS-ECH) resin was synthesized. After the reaction was completed, the product was filtered, washed with ethyl alcohol and deionized water and dried in vacuum. The two novel polymeric ligands (CCTS-ECH-DHSalophen and CCTS-ECH-DHDPE) were synthesized by the reaction of CCTS-ECH with N,N??-bis(2,5 dihydroxybenzylidene)-1,2-diaminobenzene (DHSalophen), and N,N??-bis(2,5 dihydroxybenzylidene)-4,4??-diaminodiphenylether (DHDPE). The structures of the ligands were characterized by elemental analysis, infrared spectroscopy(FT-IR), scanning electron microscopy(SEM) and thermogravimetric analysis (TGA/DTA). Adsorption experiments (pH dependency, kinetics, and equilibrium) of compounds toward Cr(VI) from waste water were carried out at 25?°C.  相似文献   

17.
Vascular ischemia/reperfusion injury (IRI) contributes to graft failure and adverse clinical outcomes following coronary artery bypass grafting. Sodium-glucose-cotransporter (SGLT)-2-inhibitors have been shown to protect against myocardial IRI, irrespective of diabetes. We hypothesized that adding canagliflozin (CANA) (an SGLT-2-inhibitor) to saline protects vascular grafts from IRI. Aortic rings from non-diabetic rats were isolated and immediately mounted in organ bath chambers (control, n = 9–10 rats) or underwent cold ischemic preservation in saline, supplemented either with a DMSO vehicle (IR, n = 8–10 rats) or 50µM CANA (IR + CANA, n = 9–11 rats). Vascular function was measured, the expression of 88 genes using PCR-array was analyzed, and feature selection using machine learning was applied. Impaired maximal vasorelaxation to acetylcholine in the IR-group compared to controls was significantly ameliorated by CANA (IR 31.7 ± 3.2% vs. IR + CANA 51.9 ± 2.5%, p < 0.05). IR altered the expression of 17 genes. Ccl2, Ccl3, Ccl4, CxCr4, Fos, Icam1, Il10, Il1a and Il1b have been found to have the highest interaction. Compared to controls, IR significantly upregulated the mRNA expressions of Il1a and Il6, which were reduced by 1.5- and 1.75-fold with CANA, respectively. CANA significantly prevented the upregulation of Cd40, downregulated NoxO1 gene expression, decreased ICAM-1 and nitrotyrosine, and increased PECAM-1 immunoreactivity. CANA alleviates endothelial dysfunction following IRI.  相似文献   

18.
In this work, Fe3O4@SiO2 nanoparticles were coated with mesoporous silica shell by SN+I pathway by using anionic surfactant (S) and co-structure directing agent (N+). The role of co-structure directing agent (CSDA) is to assist the electrostatic interaction between negatively charged silica layers and the negatively charged surfactant molecules. Prior to the mesoporous shell formation step, magnetic cores were coated with a dense silica layer to prevent iron oxide cores from leaching into the mother system under any acidic circumstances. However, it was found that both dense and mesoporous coating parameters affect the textural properties of the produced mesoporous silica shell (i.e., surface area, pore volume and shell thickness). The synthesized Fe3O4@SiO2@m-SiO2 (MCMSS) nanoparticles have been characterized by low-angle X-ray diffraction, transmission electron microscopy (TEM), and N2 adsorption-desorption analysis, and magnetic properties. The synthesized particles had dense and mesoporous silica shells of 8–37 nm and 26–50 nm, respectively. Furthermore, MCMSS possessed surface area of ca. 259–621 m2·g−1, and pore volume of ca. 0.216–0.443 cc·g−1. MCMSS showed docetaxcel cancer drug storage capacity of 25–33 w/w% and possessed control release from their mesochannels which suggest them as proper nanocarriers for docetaxcel molecules.  相似文献   

19.
Nonsteroidal anti-inflammatory drugs (NSAIDs) belong to a class of universally and commonly used anti-inflammatory analgesics worldwide. A diversity of drawbacks of NSAIDs have been reported including cellular oxidative stress, which in turn triggers the accumulation of unfolded proteins, enhancing endoplasmic reticulum stress, and finally resulting in renal cell damage. Cordyceps cicadae (CC) has been used as a traditional medicine for improving renal function via its anti-inflammatory effects. N6-(2-hydroxyethyl)adenosine (HEA), a physiologically active compound, has been reported from CC mycelia (CCM) with anti-inflammatory effects. We hypothesize that HEA could protect human proximal tubular cells (HK–2) from NSAID-mediated effects on differential gene expression at the mRNA and protein levels. To verify this, we first isolated HEA from CCM using Sephadex® LH–20 column chromatography. The MTT assay revealed HEA to be nontoxic up to 100 µM toward HK–2 cells. The HK–2 cells were pretreated with HEA (10–20 µM) and then insulted with the NSAIDs diclofenac (DCF, 200 µM) and meloxicam (MXC, 400 µM) for 24 h. HEA (20 µM) effectively prevented ER stress by attenuating ROS production (p < 0.001) and gene expression of ATF–6, PERK, IRE1α, CDCFHOP, IL1β, and NFκB within 24 h. Moreover, HEA reversed the increase of GRP78 and CHOP protein expression levels induced by DCF and MXC, and restored the ER homeostasis. These results demonstrated that HEA treatments effectively protect against DCF- and MXC-induced ER stress damage in human proximal tubular cells through regulation of the GRP78/ATF6/PERK/IRE1α/CHOP pathway.  相似文献   

20.
Cubic delta-tantalum nitride (δ-TaN) nanoparticles were selectively prepared using a K2TaF7 + (5 + k) NaN3 + kNH4F reactive mixture (k being the number of moles of NH4F) via a combustion process under a nitrogen pressure of 2.0 MPa. The combustion temperature, when plotted as a function of the number of moles of NH4F used, was in the range of 850°C to 1,170°C. X-ray diffraction patterns revealed the formation of cubic δ-TaN nanoparticles at 850°C to 950°C when NH4F is used in an amount of 2.0 mol (or greater) in the combustion experiment. Phase pure cubic δ-TaN synthesized at k = 4 exhibited a specific surface area of 30.59 m2/g and grain size of 5 to 10 nm, as estimated from the transmission electron microscopy micrograph. The role of NH4F in the formation process of δ-TaN is discussed with regard to a hypothetical reaction mechanism.  相似文献   

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